Naltrexone hydrochloride is an opioid antagonist. The compound and methods for the synthesis of naltrexone are described in U.S. Pat. No. 3,332,950. Naltrexone hydrochloride (CAS: 16676-29-2) has the molecular formula C20H23NO4.HCl and the following structural formula:

Naltrexone hydrochloride is commercially available in tablet form (Revia®, Duramed) for the treatment of alcohol dependence and for the blockade of the effects of exogenously administered opioids, i.e. the maintenance of abstinence from opioids after opioid detoxification. A dosage of 50 mg Revia® purportedly blocks the pharmacological effects of 25 mg IV administered heroin for up to 24 hours.
There is a need for new crystalline forms of naltrexone hydrochloride. The discovery of new crystalline forms of a pharmaceutical compound provides an opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the repertoire of materials that a formulation scientist has available for designing, for example, a pharmaceutical dosage form of a drug with a targeted release profile or other desirable characteristic.
WO/04108084 discloses polymorph forms of naltrexone base, however, naltrexone base and naltrexone hydrochloride are different molecular species and therefore do not possess the same solid-state properties.
All documents cited herein, including the foregoing, are incorporated by reference in their entireties for all purposes.